The present invention relates to impurity introduction methods and apparatuses thereof to introduce, in a low temperature range (temperature range of, for example, 250xc2x0 C. to very low temperature), impurity composed of atoms and molecules to a surface portion of a solid sample such as a semiconductor substrate, and also relates to manufacturing methods of a semiconductor device using such impurity introduction method.
As a technique to introduce impurity to the surface portion of the solid sample, plasma doping method in which impurity is ionized and introduced to a solid with low energy is known as disclosed in, for example, U.S. Pat. No. 4,912,065.
Now, a plasma doping method will be described below as a conventional impurity introduction method with reference to FIG. 8.
FIG. 8 illustrates a schematic structure of an impurity introduction apparatus used for the conventional plasma doping. FIG. 8 shows a vacuum chamber 10, a sample holder 11 provided inside the vacuum chamber 10 for holding a solid sample 12 which is composed of a silicon substrate or the like and to which impurity is introduced, a pressure reducing pump 13 for reducing the pressure inside the vacuum chamber 10, a source gas feed 14 for supplying doping gas including a desired element, such as B2H6, to the vacuum chamber 10, a microwave guide 15 connected to the vacuum chamber 10, a quartz plate 16 provided between the vacuum chamber 10 and the microwave guide 15, and an electromagnet 17 arranged outside the vacuum chamber 10. The microwave guide 15, the quartz plate 16 and the electromagnet 17 constitute plasma generation means. In FIG. 8, a plasma region 18 and a high-frequency power supply 19 connected to the sample holder 11 through a capacitor 20 are also shown.
In the impurity introduction apparatus having the structure above, the doping gas such as B2H6 introduced from the source gas feed 14 is made into plasma by the plasma generation means, and boron ions in the plasma are introduced to the surface portion of the solid sample 12 by the high-frequency power supply 19.
After a metal interconnection layer is formed on the solid sample 12 having thus introduced impurity, a thin oxide film is formed on the metal interconnection layer in the prescribed oxidizing atmosphere. There-after, a gate electrode is formed on the solid sample 12 by a CVD device or the like to obtain, for example, a MOS transistor.
There is a problem that in general the gas including the impurity which becomes electrically active when introduced to the solid sample such as a silicon substrate, such as the doping gas composed of B2H6, is highly dangerous.
In addition, under the plasma doping method, all the substances included in the doping gas are introduced to the solid sample. Taking as an example the doping gas composing B2H6, although only boron is the effective impurity when introduced to the solid sample, hydrogen is also introduced to the solid sample at the same time. If hydrogen is introduced to the solid sample, a lattice defect is undesirably generated at the solid sample during the thermal treatment such as epitaxial growth performed thereafter.
Therefore, the inventors of the present invention have conceived that an impurity solid including the impurity which becomes electrically active when introduced to the solid sample is arranged in the vacuum chamber, and plasma of rare gas as inert or reactive gas is generated in the vacuum chamber and the impurity solid is sputtered by ions of the rare gas so that the impurity is separated from the impurity solid.
FIG. 9. shows a schematic structure of an impurity introduction apparatus used for plasma doping which utilizes an impurity solid including impurity. The elements in FIG. 9 identical to those in FIG. 8 are denoted by the identical numerals and description thereof will not be repeated.
This impurity introduction apparatus is characterized in that the device is provided with a solid holder 22 for holding an impurity solid 21 including impurity such as boron and a rare gas feed 23 for introducing rare gas into the vacuum chamber 10. When gas such as Ar gas is introduced into the vacuum chamber 10 from the rare gas feed 23, the Ar gas is made into plasma by the plasma generation means and boron is sputtered from the impurity solid 21 by the Ar ions in the Ar plasma. Boron thus sputtered is mixed into the Ar plasma to become plasma doping gas and then introduced to the surface portion of the solid sample 12.
However, although it is true that impurity is generated from the impurity solid 21 when the plasma doping is carried out as described above, problems still remain that throughput is not satisfactory because the amount of impurity generated is not sufficient and that the impurity cannot be introduced to the region extremely close to the surface at the surface portion of the solid sample.
In view of the above, a first object of the present invention is to improve throughput by increasing the amount of impurity generated when inert or reactive gas is introduced into a vacuum chamber to generate impurity from an impurity solid, and a second object thereof is to achieve introduction of the impurity to the region extremely close to the surface at the surface portion of a solid sample.
In order to achieve the first object, a first impurity introduction method according to the present invention comprises the steps of: holding, in a vacuum chamber, an impurity solid which includes impurity and a solid sample into which impurity is introduced; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as a cathode for the plasma, and performing sputtering of the impurity solid by ions in the plasma, so that the impurity included in the impurity solid is mixed into the plasma; and applying to the solid sample a voltage allowing the solid sample to serve as a cathode for the plasma to introduce the impurity mixed into the plasma to the surface portion of the solid sample.
According to the first impurity introduction method, the ions in the plasma advance toward the impurity solid with great energy when the voltage allowing the impurity solid to serve as a cathode for the plasma is applied to the impurity solid, so that the impurity included in the impurity solid is sputtered efficiently and mixed with high concentration into the plasma composed of the inert or reactive gas. Furthermore, since the high-concentration impurity ions mixed into the plasma advance toward the solid sample with great energy when the voltage allowing the solid sample to serve as a cathode for the plasma is applied to the solid sample, the high-concentration impurity ions are introduced to the surface portion of the solid sample. Thus, a high-concentration impurity layer can be formed with high safety without causing a lattice defect at the surface portion of the solid sample.
In order to achieve the first and second objects above, a second impurity introduction method according to the present invention comprises the steps of: holding, in a vacuum chamber, an impurity solid which includes impurity and a solid sample into which impurity is introduced; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage allowing the impurity solid to serve as a cathode for the plasma, and performing sputtering of the impurity solid by ions in the plasma, so that the impurity included in the impurity solid is mixed into the plasma; and applying to the solid sample a voltage allowing the solid sample to serve as an anode for the plasma to introduce the impurity mixed into the plasma to the solid sample.
According to the second impurity introduction method, the ions in the plasma advance toward the impurity solid with great energy when the voltage allowing the impurity solid to serve as a cathode for the plasma is applied to the impurity solid, so that the impurity included in the impurity solid is sputtered efficiently and mixed with high concentration into the plasma composed of the inert or reactive gas. Furthermore, since the high-concentration impurity ions mixed into the plasma advance toward the solid sample with small energy when the voltage allowing the solid sample to serve as an anode for the plasma is applied to the solid sample, the high-concentration impurity ions are introduced to a region extremely close to the surface at the surface portion of the solid sample. Therefore, a high-concentration impurity layer can be formed with high safety at the region extremely close to the surface at the surface portion of the solid sample without causing a lattice defect at the solid sample.
In order to achieve the second object above, a third impurity introduction method according to the present invention comprises the steps of: holding, in a vacuum chamber, an impurity solid which includes impurity and a solid sample into which impurity is introduced; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage allowing the impurity solid to serve as an anode for the plasma, and performing sputtering of the impurity solid by ions in the plasma, so that the impurity included in the impurity solid is mixed into the plasma; and applying to the solid sample a voltage allowing the solid sample to serve as an anode for the plasma to introduce the impurity mixed into the plasma to the solid sample.
According to the third impurity introduction method, the ions in the plasma advance toward the impurity solid with small energy when the voltage allowing the impurity solid to serve as an anode for the plasma is applied to the impurity solid, so that a relatively small amount of the impurity included in the impurity solid is sputtered and mixed with low concentration into the plasma composed of the inert or reactive gas. Furthermore, since the low-concentration impurity ions mixed into the plasma advance toward the solid sample with small energy when the voltage allowing the solid sample to serve as an anode for the plasma is applied to the solid sample, the low-concentration impurity ions are introduced to a region extremely close to the surface at the surface portion of the solid sample. Therefore, a low-concentration impurity layer can be formed with high safety at the region extremely close to the surface at the surface portion of the solid sample without causing a lattice defect at the solid sample.
In order to achieve the first object above, a fourth impurity introduction method according to the present invention comprises the steps of: in the vacuum chamber, providing impurity deposition means onto which impurity is deposited and holding a solid sample into which impurity is introduced; blocking in the vacuum chamber a first region, where the impurity deposition means is provided, and a second region, where the solid sample is held, from each other and then introducing gas including the impurity to the first region to form an impurity film composed of the impurity at the impurity deposition means; allowing the first and second regions to communicate with each other and then introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity film a voltage allowing the impurity film to serve as a cathode for the plasma and performing sputtering of the impurity film by ions in the plasma to mix the impurity included in the impurity film into the plasma composed of the inert or reactive gas; and applying to the solid sample a voltage allowing the solid sample to serve as a cathode for the plasma to introduce the impurity mixed into the plasma to the surface portion of the solid sample.
According to the fourth impurity introduction method, when the gas including the impurity is introduced to the first region where the impurity deposition means is provided in the vacuum chamber after the first region and the second region where the solid sample is held in the vacuum chamber are blocked from each other, impurity is deposited to the impurity deposition means to form an impurity film composed of the impurity. Then, after the first and second regions are allowed to communicate with each other, the plasma composed of the inert or reactive gas is generated inside the vacuum chamber and the voltage allowing the impurity film to serve as a cathode for the plasma is applied to the impurity film, whereby, as described above, the impurity included in the impurity film is efficiently sputtered and mixed with high concentration into the plasma composed of the inert or reactive gas. In addition, when the voltage allowing the solid sample to serve as a cathode for the plasma is applied to the solid sample, the high-concentration impurity ions are introduced to the surface portion of the solid sample, as described above. Therefore, a high-concentration impurity layer can be formed at the surface portion of the solid sample without generating a lattice defect at the solid sample.
In the first, second or fourth impurity introduction method, the voltage allowing the function to serve as a cathode for the plasma is preferably a negative voltage, and in the second or third impurity introduction method, the voltage allowing the function to serve as an anode for the plasma is preferably a voltage of 0 V or lower.
In the first through fourth impurity introduction methods, preferably, the solid sample is a semiconductor substrate composed of silicon, the impurity is arsenic, phosphorus, boron, aluminum, antimony, gallium, or indium, and the inert or reactive gas is the gas including nitrogen or argon.
A first impurity introduction apparatus according to the present invention comprises a vacuum chamber of which inside is kept vacuum, solid holding means provided in the vacuum chamber for holding an impurity solid which includes impurity, sample holding means provided in the vacuum chamber for holding a solid sample to which impurity is introduced, plasma generating means for generating plasma in the vacuum chamber, gas introducing means for introducing inert or reactive gas into the vacuum chamber, first voltage applying means for applying to the solid holding means a voltage allowing the impurity solid to serve as a cathode for the plasma, and second voltage applying means for applying to the sample holding means a voltage allowing the solid sample to serve as a cathode for the plasma.
In the first impurity introduction apparatus, when the voltage allowing the impurity solid to serve as a cathode for the plasma is applied to the solid holding means by the first voltage applying means, ions in the plasma advance toward the impurity solid with great energy, so that the impurity included in the impurity solid is efficiently sputtered and mixed with high concentration into the plasma composed of the inert or reactive gas, as described above. Furthermore, when the voltage allowing the solid sample to serve as a cathode for the plasma is applied to the sample holding means by the second voltage applying means, the high-concentration impurity ions are introduced to the surface portion of the solid sample, as described above. Therefore, with the first impurity introduction apparatus, the impurity introduction method according to claim 1 of the invention can be surely realized in which a high-concentration impurity layer can be formed with high safety at the surface portion of the solid sample without generating a lattice defect at the solid sample.
A second impurity introduction apparatus according to the present invention comprises a vacuum chamber of which inside is kept vacuum, solid holding means provided in the vacuum chamber for holding an impurity solid which includes impurity, sample holding means provided in the vacuum chamber for holding a solid sample to which impurity is introduced, plasma generating means for generating plasma in the vacuum chamber, gas introducing means for introducing inert or reactive gas into the vacuum chamber, first voltage applying means for applying to the solid holding means a voltage allowing the impurity solid to serve as a cathode for the plasma, and second voltage applying means for applying to the sample holding means a voltage allowing the solid sample to serve as an anode for the plasma.
In the second impurity introduction apparatus, when the voltage allowing the impurity solid to serve as a cathode for the plasma is applied to the solid holding means by the first voltage applying means, the impurity included in the impurity solid is efficiently sputtered and mixed with high concentration into the plasma composed of the inert or reactive gas, as described above. Furthermore, when the voltage allowing the solid sample to serve as an anode for the plasma is applied to the sample holding means by the second voltage applying means, the high-concentration impurity ions are introduced to a region extremely close to the surface at the surface portion of the solid sample, as described above. Therefore, with the second impurity introduction apparatus, the second impurity introduction method can be surely realized in which a high-concentration impurity layer can be formed with high safety at the region extremely close to the surface at the surface portion of the solid sample without generating a lattice defect at the solid sample.
A third impurity introduction apparatus according to the present invention comprises a vacuum chamber of which inside is kept vacuum, solid holding means provided in the vacuum chamber for holding an impurity solid which includes impurity, sample holding means provided in the vacuum chamber for holding a solid sample to which impurity is introduced, plasma generating means for generating plasma in the vacuum chamber, gas introducing means for introducing inert or reactive gas into the vacuum chamber, first voltage applying means for applying to the solid holding means a voltage allowing the impurity solid to serve as an anode for the plasma, and second voltage applying means for applying to the sample holding means a voltage allowing the solid sample to serve as an anode for the plasma.
In the third impurity introduction apparatus, when the voltage allowing the impurity solid to serve as an anode for the plasma is applied to the solid holding means by the first voltage applying means, a relatively small amount of the impurity included in the impurity solid is sputtered and mixed with low concentration into the plasma composed of the inert or reactive gas, as described above. Furthermore, when the voltage allowing the solid sample to serve as an anode for the plasma is applied to the sample holding means by the second voltage applying means, the low-concentration impurity ions are introduced to a region extremely close to the surface at the surface portion of the solid sample, as described above. Therefore, with the third impurity introduction apparatus, the third impurity introduction method be surely realized in which a low-concentration impurity layer can be formed with high safety at the region extremely close to the surface at the surface portion of the solid sample without generating a lattice defect at the solid sample.
In the first or second impurity introduction apparatus, preferably, the first voltage applying means further includes means for applying to the solid holding means a voltage allowing the impurity solid to serve as an anode for the plasma, and means for switching a first state in which a voltage allowing the impurity solid to serve as a cathode for the plasma is applied and a second state in which a voltage allowing the impurity solid to serve as an anode for the plasma is applied.
As a result, either of the voltages allowing the impurity solid to serve as a cathode and an anode, respectively, can be applied to the solid holding means, whereby the impurity included in the impurity solid can be mixed into the plasma composed of the inert or reactive gas with either high or low concentration.
In the first impurity introduction apparatus, preferably, the second voltage applying means further includes means for applying to the sample holding means a voltage allowing the solid sample to serve as an anode for the plasma, and means for switching a first state in which a voltage allowing the solid sample to serve as a cathode for the plasma is applied and a second state in which a voltage allowing the solid sample to serve as an anode for the plasma is applied.
Thus, either of the voltages allowing the solid sample to serve as a cathode and an anode, respectively, can be applied to the sample holding means, whereby the depth of the impurity layer formed at the surface portion of the solid sample can be controlled.
A fourth impurity introduction apparatus according to the present invention comprises a vacuum chamber of which inside is kept vacuum, impurity deposition means to which impurity is deposited, sample holding means provided in the vacuum chamber for holding a solid sample to which impurity is introduced, shutter means for blocking a first region where the impurity deposition means is provided and a second region where the sample holding means is provided from each other and allowing these regions to communicate with each other, first gas introducing means for introducing gas which includes impurity to the first region in the vacuum chamber, plasma generating means for generating plasma in the vacuum chamber, second gas introducing means for introducing inert or reactive gas into the vacuum chamber, first voltage applying means for applying to the impurity deposition means a voltage allowing the impurity deposited on the impurity deposition means to serve as a cathode for the plasma, and second voltage applying means for applying to the sample holding means a voltage allowing the solid sample to serve as a cathode for the plasma.
In the fourth impurity introduction apparatus, in the vacuum chamber the first region where the impurity deposition means is provided is blocked by the shutter means from the second region where the solid sample is held, and thereafter the gas including impurity is introduced to the first region by the first gas introducing device, whereby the impurity is deposited to the impurity deposition means to form an impurity film composed of the impurity. After the first and second regions are allowed to communicate with each other, the plasma composed of the inert or reactive gas is generated inside the vacuum chamber by the plasma generating means and the voltage allowing the impurity film to serve as a cathode for the plasma is applied to the impurity deposition means by the first voltage applying means. As a result, the impurity included in the impurity film is efficiently sputtered and mixed with high concentration into the plasma composed of the inert or reactive gas, as described above. When the voltage allowing the solid sample to serve as a cathode for the plasma is applied to the sample holding means by the second voltage applying means, the high-concentration impurity ions are introduced to the surface portion of the solid sample, as described above. Therefore, according to the fourth impurity introduction apparatus, an impurity introduction method for forming a high-concentration impurity layer at the surface portion of the solid sample without causing a lattice defect at the solid sample can be realized without preparing the impurity solid.
A fifth impurity introduction apparatus according to the present invention comprises a vacuum chamber of which inside is kept vacuum, impurity deposition means to which impurity is deposited, sample holding means provided in the vacuum chamber for holding a solid sample to which impurity is introduced, shutter means for blocking a first region where the impurity deposition means is provided and a second region where the sample holding means is provided from each other and allowing these regions to communicate with each other, first gas introducing means for introducing gas which includes impurity to the first region in the vacuum chamber, plasma generating means for generating plasma in the vacuum chamber, second gas introducing means for introducing inert or reactive gas into the vacuum chamber, first voltage applying means for applying to the impurity deposition means a voltage allowing the impurity deposited on the impurity deposition means to serve as a cathode for the plasma, and second voltage applying means for applying to the sample holding means a voltage allowing the solid sample to serve as an anode for the plasma.
In the fifth impurity introduction apparatus, in the vacuum chamber the first region where the impurity deposition means is provided is blocked by the shutter means from the second region where the solid sample is held, and thereafter the gas including impurity is introduced to the first region by the first gas introducing device, whereby the impurity is deposited to the impurity deposition means to form an impurity film composed of the impurity. After the first and second regions are allowed to communicate with each other, the plasma composed of the inert or reactive gas is generated inside the vacuum chamber by the plasma generating means and the voltage allowing the impurity film to serve as a cathode for the plasma is applied to the impurity deposition means by the first voltage applying means. As a result, the impurity included in the impurity film is efficiently sputtered and mixed with high concentration into the plasma composed of the inert or reactive gas, as described above. When the voltage allowing the solid sample to serve as an anode for the plasma is applied to the sample holding means by the second voltage applying means, the high-concentration impurity ions are introduced to the region extremely close to the surface at the surface portion of the solid sample, as described above. Therefore, according to the fifth impurity introduction apparatus, an impurity introduction method for forming a high-concentration impurity layer at the region extremely close to the surface at the surface portion of the solid sample without causing a lattice defect can be realized without preparing the impurity solid.
A sixth impurity introduction apparatus according to the present invention comprises a vacuum chamber of which inside is kept vacuum, impurity deposition means to which impurity is deposited, sample holding means provided in the vacuum chamber for holding a solid sample to which impurity is introduced, shutter means for blocking a first region where the impurity deposition means is provided and a second region where the sample holding means is provided from each other and allowing these regions to communicate with each other, first gas introducing means for introducing gas which includes impurity to the first region in the vacuum chamber, plasma generating means for generating plasma in the vacuum chamber, second gas introducing means for introducing inert or reactive gas into the vacuum chamber, first voltage applying means for applying to the impurity deposition means a voltage allowing the impurity deposited on the impurity deposition means to serve as an anode for the plasma, and second voltage applying means for applying to the sample holding means a voltage allowing the solid sample to serve as an anode for the plasma.
In the sixth impurity introduction apparatus, in the vacuum chamber the first region where the impurity deposition means is provided is blocked by the shutter means from the second region where the solid sample is held, and thereafter the gas including impurity is introduced to the first region by the first gas introducing device, whereby the impurity is deposited to the impurity deposition means to form an impurity film composed of the impurity. After the first and second regions are allowed to communicate with each other, the plasma composed of the inert or reactive gas is generated inside the vacuum chamber by the plasma generating means and the voltage allowing the impurity film to serve as an anode for the plasma is applied to the impurity deposition means by the first voltage applying means. Thus, a relatively small amount of the impurity included in the impurity film is sputtered and mixed with low concentration into the plasma composed of the inert or reactive gas, as described above. When the voltage allowing the solid sample to serve as an anode for the plasma is applied to the sample holding means by the second voltage applying means, the low-concentration impurity ions are introduced to the region extremely close to the surface at the surface portion of the solid sample, as described above. Therefore, according to the sixth impurity introduction apparatus, an impurity introduction method for forming a low-concentration impurity layer at the region extremely close to the surface at the surface portion of the solid sample without causing a lattice defect can be realized without preparing the impurity solid.
In the fourth or fifth impurity introduction apparatus, preferably the first voltage applying means further includes means for applying to the impurity deposition means a voltage allowing the impurity deposited to the impurity deposition means to serve as an anode for the plasma, and means for switching a first state where the impurity deposited to the impurity deposition means serves as a cathode for the plasma and a second state where it serves as an anode.
Consequently, either of the voltages allowing the impurity film to serve as a cathode and an anode for the plasma, respectively, can be applied to the impurity deposition means, so that the impurity included in the impurity film can be mixed with either high or low concentration into the plasma composed of the inert or reactive gas.
In the fourth impurity introduction apparatus, preferably the second voltage applying means further includes means for applying to the sample holding means a voltage which allows the solid sample to serve as an anode for the plasma, and switching means for switching a first state where the solid sample serves as a cathode for the plasma and a second state where it serves as an anode for the plasma.
Thus, either of the voltages allowing the solid sample to serve as a cathode and an anode for the plasma, respectively, can be applied to the sample holding means, so that the depth of the impurity layer formed at the surface portion of the solid sample can be controlled.
In the first, second, fourth or fifth impurity introduction apparatus, the voltage allowing the function to serve as a cathode for the plasma is preferably a negative voltage; and in the second, third, fifth or sixth impurity introduction apparatus, the voltage allowing the function to serve as an anode for the plasma is preferably a voltage of 0 V or lower.
A first method of manufacturing a semiconductor device according to the present invention comprises the steps of: electrically isolating a diode formation region on a semiconductor substrate by an element isolation layer; holding in a vacuum chamber the semiconductor substrate at which the element isolation layer is formed and an impurity solid including the impurity to be introduced into the diode formation region; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as a cathode for the plasma, performing sputtering of the impurity solid by ions in the plasma, and thereby mixing the impurity included in the impurity solid into the plasma composed of the inert or reactive gas; applying, to the semiconductor substrate held in the vacuum chamber, a voltage which allows the semiconductor substrate to serve as a cathode for the plasma and thereby introducing the impurity mixed into the plasma to a surface portion of the diode formation region at the semiconductor substrate to form an impurity layer; and, on the semiconductor substrate at which the impurity layer is formed, forming an interconnection layer electrically connected with the impurity layer.
According to the first method of manufacturing a semiconductor device, impurity can be introduced with high concentration to the surface portion of the diode formation region at the semiconductor substrate, similarly to the first impurity introduction method, so that a diode having a high-concentration impurity layer at the surface portion of the semiconductor substrate can be formed without generating a lattice defect at the semiconductor substrate and high safety is guaranteed.
A second method of manufacturing a semiconductor device according to the present invention comprises the steps of: electrically isolating a diode formation region on a semiconductor substrate by an element isolation layer; holding in a vacuum chamber the semiconductor substrate at which the element isolation layer is formed and an impurity solid including the impurity to be introduced into the diode formation region; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as a cathode for the plasma, performing sputtering of the impurity solid by ions in the plasma, and thereby mixing the impurity included in the impurity solid into the plasma composed of the inert or reactive gas; applying, to the semiconductor substrate held in the vacuum chamber, a voltage which allows the semiconductor substrate to serve as an anode for the plasma and thereby introducing the impurity mixed into the plasma to a surface portion of the diode formation region at the semiconductor substrate to form an impurity layer; and, on the semiconductor substrate at which the impurity layer is formed, forming an interconnection layer electrically connected with the impurity layer.
According to the second method of manufacturing a semiconductor device, impurity can be introduced with high concentration to a region extremely close to the surface at the surface portion of the diode formation region at the semiconductor substrate, similarly to the second impurity introduction method, so that a diode having a high-concentration impurity layer at the region extremely close to the surface portion of the semiconductor substrate can be formed without generating a lattice defect at the semiconductor substrate and high safety is guaranteed.
A third method of manufacturing a semiconductor device according to the present invention comprises the steps of: electrically isolating a diode formation region on a semiconductor substrate by an element isolation layer; holding in a vacuum chamber the semiconductor substrate at which the element isolation layer is formed and an impurity solid including the impurity to be introduced into the diode formation region; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as an anode for the plasma, performing sputtering of the impurity solid by ions in the plasma, and thereby mixing the impurity included in the impurity solid into the plasma composed of the inert or reactive gas; applying, to the semiconductor substrate held in the vacuum chamber, a voltage which allows the semiconductor substrate to serve as an anode for the plasma and thereby introducing the impurity mixed into the plasma to a surface portion of the diode formation region at the semiconductor substrate to form an impurity layer; and, on the semiconductor substrate at which the impurity layer is formed, forming an interconnection layer electrically connected with the impurity layer.
According to the third method of manufacturing a semiconductor device, impurity can be introduced with low concentration to a region extremely close to the surface at the surface portion of the diode formation region at the semiconductor substrate, similarly to the third impurity introduction method, so that a diode having a low-concentration impurity layer at the region extremely close to the surface portion of the semiconductor substrate can be formed without generating a lattice defect at the semiconductor substrate and high safety is guaranteed.
A fourth method of manufacturing a semiconductor device according to the present invention comprises the steps of: electrically isolating a transistor formation region on a semiconductor substrate by an element isolation layer; forming an electrode at the transistor formation region on the semiconductor substrate where the element isolation layer is formed with an insulating layer interposed therebetween; holding in a vacuum chamber the semiconductor substrate at which the electrode is formed and an impurity solid which includes impurity to be introduced into the transistor formation region; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as a cathode for the plasma, performing sputtering of the impurity solid by ions in the plasma, and thereby mixing the impurity included in the impurity solid to the plasma composed of the inert or reactive gas; applying, to the semiconductor substrate held in the vacuum chamber, a voltage which allows the semiconductor substrate to serve as a cathode for the plasma, and thereby introducing the impurity mixed into the plasma to the surface portion of the transistor formation region at the semiconductor substrate to form an impurity layer; and forming an interconnection layer electrically connected with the electrode of the semiconductor substrate where the impurity layer is formed.
According to the fourth method of manufacturing a semiconductor device, similarly to the first impurity introduction method, the impurity can be introduced with high concentration to the surface portion of the transistor formation region at the semiconductor substrate, whereby a transistor having a high-concentration impurity layer at the surface portion of the semiconductor substrate can be formed without generating a lattice defect at the semiconductor substrate and high safety is guaranteed.
A fifth method of manufacturing a semiconductor device according to the present invention comprises the steps of: electrically isolating a transistor formation region on a semiconductor substrate by an element isolation layer; forming an electrode at the transistor formation region on the semiconductor substrate where the element isolation layer is formed with an insulating layer interposed therebetween; holding in a vacuum chamber the semiconductor substrate at which the electrode is formed and an impurity solid which includes impurity to be introduced into the transistor formation region; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as a cathode for the plasma, performing sputtering of the impurity solid by ions in the plasma, and thereby mixing the impurity included in the impurity solid to the plasma composed of the inert or reactive gas; applying, to the semiconductor substrate held in the vacuum chamber, a voltage which allows the semiconductor substrate to serve as an anode for the plasma, and thereby introducing the impurity mixed into the plasma to the surface portion of the transistor formation region at the semiconductor substrate to form an impurity layer; and forming an interconnection layer electrically connected with the electrode of the semiconductor substrate where the impurity layer is formed.
According to the fifth method of manufacturing a semiconductor device, similarly to the second impurity introduction method, the impurity can be introduced with high concentration to a region extremely close to the surface at the surface portion of the transistor formation region at the semiconductor substrate, whereby a transistor having a high-concentration impurity layer in the region extremely close to the surface at the surface portion of the semiconductor substrate can be formed without generating a lattice defect at the semiconductor substrate and high safety is guaranteed.
A sixth method of manufacturing a semiconductor device according to the present invention comprises the steps of: electrically isolating a transistor formation region on a semiconductor substrate by an element isolation layer; forming an electrode at the transistor formation region on the semiconductor substrate where the element isolation layer is formed with an insulating layer interposed therebetween; holding in a vacuum chamber the semiconductor substrate at which the electrode is formed and an impurity solid which includes impurity to be introduced into the transistor formation region; introducing inert or reactive gas into the vacuum chamber to generate plasma composed of the inert or reactive gas; applying to the impurity solid a voltage which allows the impurity solid to serve as an anode for the plasma, performing sputtering of the impurity solid by ions in the plasma, and thereby mixing the impurity included in the impurity solid to the plasma composed of the inert or reactive gas; applying, to the semiconductor substrate held in the vacuum chamber, a voltage which allows the semiconductor substrate to serve as an anode for the plasma, and thereby introducing the impurity mixed into the plasma to the surface portion of the transistor formation region at the semiconductor substrate to form an impurity layer; and forming an interconnection layer electrically connected with the electrode of the semiconductor substrate where the impurity layer is formed.
According to the sixth method of manufacturing a semiconductor device, similarly to the third impurity introduction method, the impurity can be introduced with low concentration to a region extremely close to the surface at the surface portion of the transistor formation region at the semiconductor substrate, whereby a transistor having a low-concentration impurity layer in the region extremely close to the surface at the surface portion of the semiconductor substrate can be formed without generating a lattice defect at the semiconductor substrate and high safety is guaranteed.
In the first, second, fourth or fifth method of manufacturing a semiconductor device, the voltage allowing the function to serve as a cathode for the plasma is preferably a negative voltage; and in the second, third, fourth or fifth method of manufacturing a semiconductor device, the voltage allowing the function to serve as an anode for the plasma is preferably a voltage of 0 V or lower.
In the first to sixth methods of manufacturing a semiconductor device, preferably, the semiconductor substrate is composed of silicon, the impurity is arsenic, phosphorus, boron, aluminum, antimony, gallium, or indium, and the inert or reactive gas is the gas including nitrogen or argon.